Making explicit and unclear generality

Mentioning the specific with the general can be for a variety of reasons.
First, it might be because of a certain specialty which does not exist
in the rest of the individuals which form the general, as was in the case
of Nooh, Ibraheem, Musa and 'Eesa. In another time, it might be because
the general is indefinite and one cannot understand the detail
of its generality as in His (SWT) saying,

A guidance to those who are protecting themselves from the punishment
of Allah by warding off evil. Who believe in al-Ghayb (the Unseen),
establish As-Salaat, and spend out of what We have provided for them.
And who believe in that which has been sent down (revealed) to
you (Muhammad SAWS) and in that which was sent down (revealed) before you.
[Al-Baqarah:2-5]

His saying "They believe in al-Ghayb (the Unseen)" comprises all the unseen
which one should believe in; however it is rather indefinite. There is
not in it any indication that part of the Unseen is: "What has
been revealed to you (Muhammad SAWS) and what has been revealed before
you." It might also mean that they believe in the reported subject, that
is al-Ghayb, and in the reporting about al-Ghayb, and that is "what has
been revealed to you (Muhammad SAWS) and what has been revealed before
you."